Field of the Invention
The present invention relates to an image displaying system which projects a projection image from each of a plurality of projection-type image displaying apparatuses to a screen so as to overlap parts of the respective projection images and displays an image constituted by the projection images on the screen, a controlling method of the image displaying system. Moreover, the present invention relates to a program which is used to cause a computer to perform the controlling method of the image displaying system.
Description of the Related Art
Conventionally, in case of constituting a multi-view screen by using a plurality of projection-type image displaying apparatuses, an image overlap region in which respective parts of projection images projected by the adjacent projection-type image displaying apparatuses overlap each other is provided, and luminance correction is performed to image signals in the image overlap region, thereby making the seam at the overlap portion inconspicuous.
Here, there is a method of electrically performing the luminance correction. In such electrical luminance correction, for example, in case of linearly reducing the luminance toward the image edge in the image overlap region, it is necessary, in consideration of a so-called display γ (gamma) characteristic, to have an output image signal Vo as calculated by the following expression (1):Vo=((x/W)^γ)*Vi  (1)
In the expression (1), “Vi” indicates an input image signal, “W” indicates the width of the image overlap region, and “x” indicates the distance from the image edge of the image overlap region.
As can be understood from the expression (1), the synthesized luminance in the image overlap region is influenced by the display γ characteristic of each projection-type image displaying apparatus. Such a state will be described hereinafter with reference to FIGS. 11A, 11B and 11C.
FIGS. 11A to 11C are the diagrams for describing the luminance characteristics of the image overlap region. Here, it is assumed in FIGS. 11A to 11C that the display γ characteristic of one of the adjacent projection-type image displaying apparatuses is a display γ1 characteristic and the display γ characteristic of the other of the adjacent projection-type image displaying apparatuses is a display γ2 characteristic.
As illustrated in FIG. 11A, when the display γ1 and γ2 characteristics coincide with the display γ characteristic of the expression (1), the luminance correction characteristic of the image overlap region on the left screen and the luminance correction characteristic of the image overlap region on the right screen are cancelled each other, so that the synthesized luminance of the image overlap region becomes uniform. However, if one of the display γ characteristics is small as in the case of γ1<γ, the synthesized luminance in the vicinity of the center of the image overlap region raises as illustrated in FIG. 11B. On the other hand, if one of the display γ characteristics is large as in the case of γ1>γ, the synthesized luminance in the vicinity of the center of the image overlap region lowers as illustrated in FIG. 11C.
Under the circumstances, for example, Japanese Patent Application Laid-Open No. 2002-238064 discloses the technique by which the image with the predetermined gradation is entirely displayed and photographed by the camera for each projection-type image displaying apparatus, and the synthesized luminance is made uniform by setting the correct display γ characteristic from the photographed image.
The technique disclosed in Japanese Patent Application Laid-Open No. 2002-238064 is to adjust the display γ characteristic for each projection-type image displaying apparatus by the measurement. However, in a case where the luminance correction characteristic of the image overlap region on the own screen to which one projection image is projected and the luminance correction characteristic of the image overlap region on the other screen to which the other projection image is projected are not in the relation of cancellation, the synthesized luminance of the image overlap region is not uniform yet.
The present invention has been completed in consideration of such a problem as described above, and aims to provide a mechanism which enables to uniform the synthesized luminance in the image overlap region of the projection image by a simple process.